1. Field of the Invention
The invention relates to a vehicular bumper beam system and, more specifically, to a bumper beam system that maximizes both front and angled barrier low speed impact performance while allowing vehicle rails to be brought forward and closer to an exterior fascia therefor.
2. Related Art
Current and future trends in styling for vehicles are tending toward increase curvature on the front (and sometimes) rear ends of vehicles. As this curvature increases, a bumper system for either the front or rear of the vehicle should be configured to effectively shield the transverse face of the vehicle from impact. In known prior art bumper systems, the bumper beam typically comprises a laterally-extending unitary beam member mounted near each end to outer (e.g., forward) ends of vehicle structural rails in a xe2x80x9cB-sectionxe2x80x9d bumper beam or flush-mounted in a stamped version of a bumper beam.
For example, a B-section beam mounts in front of the vehicular structural rails, i.e., to the forward ends thereof and, in order to improve packaging space is end formed. The B-section-type beam works well in frontal barrier impacts because of its high stiffness. But this high stiffness of the B-section-type beam can be detrimental in angled barrier impacts as it increases the load on the structural rails and absorbs less energy from these side direction impacts. In addition, this type of beam takes up more room and reduces the amount of foam that can be used as an energy-absorbing beam.
Conversely, the stamping-type of beam typically performs worse on frontal barrier impacts as it typically has less stiffness than a B-section-type beam. Further, this type of beam does not perform well in angled barrier impacts because this type of beam is flush-mounted to the rail. However, the stamped-type bumper beam does allow more packaging space within the bumper system to allow for a maximum amount of foam to be added to absorb the energy of an impact.
An example configuration of a front mounted B-section-type beam is shown in U.S. Pat. No. 6,042,163. This reference describes a bumper in which an end piece is welded on the end of a curved beam. The rear wall of the end piece is, in turn, welded to the forward end of structural rails or other components (xe2x80x9cstays 23xe2x80x9d) which extend outward from the vehicle and are used to mount the bumper to the vehicle. The end pieces thus serve to position a curved bumper beam in front of flat-ended structural components extending from the vehicle and to mount the curved bumper beam to those structural components.
This configuration suffers from a number of deficiencies. To the extent that structural components extending outward from the vehicle (which are typically designed as additional crushable energy-absorbing components) are lengthened to increase their energy-absorbing capability, the design of such end caps requires the bumper to protrude further from the vehicle, thus increasing the overall vehicle length and the overall bulk of the bumper components. This, in turn, limits vehicle designers by limiting any attempts to streamline or otherwise minimize the appearance of the bumper.
The design of these prior art end pieces also rely on the structure of the B-section beam for their energy management during an offset or corner impact, and do not provide for any additional energy-absorbing structure.
Finally, the design of these prior art end pieces do not allow an engineer to separately optimize bumper configurations for both forward and offset and corner impacts. With this prior art configuration, designing the B-section-type beam and structural components extending outward from the vehicle to improve forward impact resistance may result in poorer offset or side impact resistance, without allowing the engineer to separately tune or alter the components to adjust for the different types of impacts.
To achieve 5-star compliance for high speed impact, the length of the vehicle structural rails have been increased without an increase in overall vehicle length. This has reduced the space available for an effective energy management/bumper system to fit into the available space between a vehicle fascia and the engine components without affecting styling (such as that required when the vehicle fascia has a high degree of curvature). Moreover, in such high-speed impacts, the structural rails are designed to carry much of the energy. A component that allows the engineer to direct the energy away from the bumper beam and more directly to the structural rails, or to provide a separate xe2x80x9ccrush spacexe2x80x9d with different parameters or characteristics than those of the bumper beam in front of the structural rails, would therefore be advantageous.
The invention relates to a vehicular bumper beam system and, more specifically, to a bumper beam system that maximizes both front and angled barrier low speed impact performance while allowing vehicle rails to be brought forward and closer to an exterior fascia therefor and, thus, requires a lower vehicle length. The invention overcomes the limitations of the prior art by contemplating a xe2x80x9cfloatingxe2x80x9d center beam which is interconnected to vehicular rails by adapter elements, referred to as end caps which provide many benefits over prior art bumper systems.
Other objects, features, and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings.